There is a general need for high data density optical recording media. One possibility to increase the data density is to use physical effects that allow to reach a resolution beyond the diffraction limit of the reading light. Recently it has been shown that the electric field intensity near a metallic tip can be strongly enhanced. See, for example, A. Bouhelier et al.: “Near field second harmonic generation induced by local field enhancement”, Phys. Rev. Lett. 90, Num. 3 (2003) 013903-1. In E. J. Sánchez et al: “Near-Field Fluorescence Microscopy Based on Two-Photon Excitation with Metal Tips”, Phys. Rev. Lett. 82, Num. 20 (1999), pp. 4014 an enhancement by a factor of 1000 to 3000 is reported. To efficiently excite these electric fields, preferably a radially polarized doughnut shaped beam is used. Such a doughnut shaped beam has a reduced spot size. For example, with NA=0.9 the spot size (diameter) generated by the longitudinal field is reduced by a factor of 1.22. See J. Stadler et al.: “Tighter focusing with a parabolic mirror”, Opt. Lett. 33, Num. 7 (2008), pp. 681.